The present invention relates to a novel license plate lamp and, in particular, to a technique in which, even if a license plate lamp is mounted on different vehicle bodies, the license display surface of the license plate lamp can be illuminated substantially uniformly.
Conventionally, a license plate lamp comprises a light source body including a light emitting part, a lens body including a group of lenses, and a lamp body, and is to be mounted on the neighboring portion of the license display surface of a license plate which is installed to the rear end portion of a vehicle body. And, in this license plate lamp, the light that is radiated directly from the light emitting part (which is hereinafter referred to as "direct light") is controlled by the lens group to thereby form a light flux for illumination (which is hereinafter referred to as "illumination light flux"), while the license display surface is illuminated by the thus formed illumination light flux in such a manner that an illumination ratio of the brightest spot to the darkest spot should be confined to or less than 20 to 1, that is, in the range of a so called safety reference value or less.
By the way, in a conventional license plate lamp, there is prepared only one position relationship between the lens group and the license display surface that allows the license display surface to be illuminated by the illumination light flux controlled by the lens group.
Therefore, in the above-mentioned conventional license plate lamp, if the vehicle body to which the license plate lamp is to be mounted is changed to another and the position relationship between the lens group and the license display surface is thereby changed, then the illumination light flux controlled by the lens group is displaced from the license display surface, which makes it impossible that the license display surface is illuminated by the illumination light flux. Due to this, the license plate lamp cannot be used as a part which can be used in common among different vehicle bodies and thus different license plate lamps must be prepared for the respective different vehicle bodies.